Per Pon o:
Do you expect this to be a growing problem in the future? I don't
remember feral cats being a problem until a few yrs. ago.

Maybe it's a local predator/prey balance thing.

I have no clue what preys on cats except for foxes.

Having said that, we used to have a lot more cats around here
until a family of foxes moved in to the area (as evidenced by
security camera videos). Now the cat population seems pretty
much restricted to cats whose owners keep them in at night.

Even during the day, we see the occasional fox prowling around...
and we always have a door or two open so our cat has a fallback
position.
--
Pete Cresswell